The decanoate esters of nandrolone, testosterone, and trenbolone induce steroid specific memory impairment and somatic effects in the male rat.

Long-term use of anabolic androgenic steroids (AAS) in supratherapeutic doses is associated with severe adverse effects, including physical, mental, and behavioral alterations. When used for recreational purposes several AAS are often combined, and in scientific studies of the physiological impact of AAS either a single compound or a cocktail of several steroids is often used. Because of this, steroid-specific effects have been difficult to define and are not fully elucidated. The present study used male Wistar rats to evaluate potential somatic and behavioral effects of three different AAS; the decanoate esters of nandrolone, testosterone, and trenbolone. The rats were exposed to 15 mg/kg of nandrolone decanoate, testosterone decanoate, or trenbolone decanoate every third day for 24 days. Body weight gain and organ weights (thymus, liver, kidney, testis, and heart) were measured together with the corticosterone plasma levels. Behavioral effects were studied in the novel object recognition-test (NOR-test) and the multivariate concentric square field-test (MCSF-test). The results conclude that nandrolone decanoate, but neither testosterone decanoate nor trenbolone decanoate, caused impaired recognition memory in the NOR-test, indicating an altered cognitive function. The behavioral profile and stress hormone level of the rats were not affected by the AAS treatments. Furthermore, the study revealed diverse AAS-induced somatic effects i.e., reduced body weight development and changes in organ weights. Of the three AAS included in the study, nandrolone decanoate was identified to cause the most prominent impact on the male rat, as it affected body weight development, the weights of multiple organs, and caused an impaired memory function.

Nandrolone decanoate and testosterone undecanoate differently affect stress hormones, neurotransmitter systems, and general activity in the male rat.

Anabolic androgenic steroids (AAS) are frequently used to improve physical appearance and strength. AAS are known to affect muscle growth, but many AAS-users also experience psychiatric and behavioral changes after long-term use. The AAS-induced effects on the brain seem to depend on the type of steroid used, but the rationale behind the observed effect is still not clear. The present study investigated and compared the impact of nandrolone decanoate and testosterone undecanoate on body weight gain, levels of stress hormones, brain gene expression, and behavioral profiles in the male rat. The behavioral profile was determined using the multivariate concentric squared field test (MCSF-test). Blood plasma and brains were collected for further analysis using ELISA and qPCR. Nandrolone decanoate caused a reduction in body weight gain in comparison with both testosterone undecanoate and control. Rats receiving nandrolone decanoate also demonstrated decreased general activity in the MCSF. In addition, nandrolone decanoate reduced the plasma levels of ACTH in comparison with the control and increased the levels of corticosterone in comparison with testosterone undecanoate. The qPCR analysis revealed brain region-dependent changes in mRNA expression, where the hypothalamus was identified as the region most affected by the AAS. Alterations in neurotransmitter systems and stress hormones may contribute to the changes in behavior detected in the MCSF. In conclusion, both AAS affect the male rat, although, nandrolone decanoate has more pronounced impact on the physiological and the behavioral parameters measured.

Sex-Specific Effects of Acute Ethanol Exposure on Locomotory Activity and Exploratory Behavior in Adult Zebrafish (Danio rerio).

The zebrafish (Danio rerio) is an established model organism in pharmacology and biomedicine, including in research on alcohol use disorders and alcohol-related disease. In the past 2 decades, zebrafish has been used to study the complex effects of ethanol on the vertebrate brain and behavior in both acute, chronic and developmental exposure paradigms. Sex differences in the neurobehavioral response to ethanol are well documented for humans and rodents, yet no consensus has been reached for zebrafish. Here, we show for the first time that male zebrafish of the AB strain display more severe behavioral impairments than females for equal exposure concentrations. Adult zebrafish were immersed in 0, 1 or 2% (v/v) ethanol for 30 min, after which behavior was individually assessed in the zebrafish Multivariate Concentric Square Field™ (zMCSF) arena. Males exposed to 2% ethanol showed clear signs of sedation, including reduced activity, increased shelter seeking and reduced exploration of shallow zones. The 1% male group displayed effects in the same direction but of smaller magnitude; this group also explored the shallow areas less, but did not show a general reduction in activity nor an increase in shelter seeking. By contrast, 1 and 2% exposed females showed no alterations in explorative behavior. Females exposed to 2% ethanol did not display a general reduction in activity, rather activity gradually increased from hypoactivity to hyperactivity over the course of the test. This mixed stimulatory/depressant effect was only quantifiable when locomotory variables were analyzed over time and was not apparent from averages of the whole 30-min test, which may explain why previous studies failed to detect sex-specific effects on locomotion. Our results emphasize the importance of explicitly including sex and time as factors in pharmacological studies of zebrafish behavior. We hypothesize that the lower sensitivity of female zebrafish to ethanol may be explained by their greater body weight and associated larger distribution volume for ethanol, which may render lower brain ethanol concentrations in females.

Functional connectivity in reward-related networks is associated with individual differences in gambling strategies in male Lister hooded rats.

Individuals with gambling disorder display deficits in decision-making in the Iowa Gambling Task. The rat Gambling Task (rGT) is a rodent analogue that can be used to investigate the neurobiological mechanisms underlying gambling behaviour. The aim of this explorative study was to examine individual strategies in the rGT and investigate possible behavioural and neural correlates associated with gambling strategies. Thirty-two adult male Lister hooded rats underwent behavioural testing in the multivariate concentric square field™ (MCSF) and the novel cage tests, were trained on and performed the rGT and subsequently underwent resting-state functional magnetic resonance imaging (R-fMRI). In the rGT, stable gambling strategies were found with subgroups of rats that preferred the suboptimal safest choice as well as the disadvantageous choice, that is, the riskiest gambling strategy. R-fMRI results revealed associations between gambling strategies and brain regions central for reward networks. Moreover, rats with risky gambling strategies differed from those with strategic and intermediate strategies in brain functional connectivity. No differences in behavioural profiles, as assessed with the MCSF and novel cage tests, were observed between the gambling strategy groups. In conclusion, stable individual differences in gambling strategies were found. Intrinsic functional connectivity using R-fMRI provides novel evidence to support the notion that individual differences in gambling strategies are associated with functional connectivity in brain regions important for reward networks.

Behavioral Profiles of Adolescent Alcohol-Preferring/Non-preferring (P/NP) and High/Low Alcohol-Drinking (HAD/LAD) Rats Are Dependent on Line but Not Sex.

Initial contact with alcohol generally occurs during adolescence, and high consumption during this period is associated with increased risk for later alcohol (AUDs) and/or substance use disorders (SUDs). Rodents selectively bred for high or low alcohol consumption are used to identify behavioral characteristics associated with a propensity for high or low voluntary alcohol intake. The multivariate concentric square field™ (MCSF) is a behavioral test developed to study rodents in a semi-naturalistic setting. Testing in the MCSF creates a comprehensive behavioral profile in a single trial. The current aim was to examine the behavioral profiles of adolescent, bidirectionally selectively bred male and female high alcohol-consuming (P and HAD1/2) and low alcohol-consuming (NP and LAD1/2) rat lines, and outbred Wistar rats. Alcohol-naïve rats were tested once in the MCSF at an age between postnatal days 30 and 35. No common behavioral profile was found for either high or low alcohol-consuming rat lines, and the effect of sex was small. The P/NP and HAD2/LAD2 lines showed within pair-dependent differences, while the HAD1/LAD1 lines were highly similar. The P rats displayed high activity and risk-associated behaviors, whereas HAD2 rats displayed low activity, high shelter-seeking behavior, and open area avoidance. The results from P rats parallel clinical findings that denser family history and risk-taking behavior are strong predictors of future AUDs, often with early onset. Contrarily, the HAD2 behavioral profile was similar to individuals experiencing negative emotionality, which also is associated with a vulnerability to develop, often with a later onset, AUDs and/or SUDs.

The effects of age, sex, and handling on behavioral parameters in the multivariate concentric square field™ test.

The multivariate concentric square field™ (MCSF) is a complex and ethologically relevant apparatus that is designed to measure several behavioral parameters within the same test session including risk-taking, risk-assessment, shelter-seeking (anxiety relieving), exploration, and general activity. While several studies have behaviorally and pharmacologically validated the use of the MCSF in adults, far fewer have used adolescents. Given the well-established link between adolescence and risk-taking, it is important to validate use of the MCSF in adolescence. The present study compared the effects of age, sex, and handling on behavioral categories in the MCSF. In addition, principal component analyses were used to compare the underlying behavioral components in adolescent and adult Sprague-Dawley rats. Results revealed that handling increased risk-taking and reduced shelter-seeking. Females were more exploratory than males, but no compelling age differences in risk-taking or risk-assessment were found. Principal component analyses revealed six major principal components for both adolescents and adults with the first and second components consisting mainly of center/center circle, risk-assessment, and shelter-seeking variables in adolescence, and general activity and center/center circle variables in adults. These results confirm age differences in the underlying behavioral components in the MCSF.

Behavioral Profiling in Early Adolescence and Early Adulthood of Male Wistar Rats After Short and Prolonged Maternal Separation.

Early-life stress and its possible correlations to genes, environment, and later health outcomes can only be studied retrospectively in humans. Animal models enable the exploration of such connections with prospective, well-controlled study designs. However, with the recent awareness of replicability issues in preclinical research, the reproducibility of results from animal models has been highlighted. The present study aims to reproduce the behavioral effects of maternal separation (MS) previously observed in the multivariate concentric square fieldTM (MCSF) test. A second objective was to replicate the adolescent behavioral profiles previously described in the MCSF test. Male rats, subjected to short or prolonged MS or standard rearing, were subjected to behavioral testing in early adolescence and early adulthood. As seen in previous studies, the behavioral effects of MS in the MCSF were small at both tested time points. When tested in early adolescence, the animals exhibited a similar behavioral profile as previously seen, and the finding of adolescent behavioral types was also reproduced. The distribution of animals into the behavioral types was different than in the initial study, but in a manner consistent with developmental theories, as the current cohort was younger than the previous. Notably, the Shelter seeker behavioral type persisted through development, while the Explorer type did not. The lack of basal behavioral effect after MS is in line with the literature on this MS paradigm; the working hypothesis is that the prolonged MS gives rise to a phenotype predisposed to negative health outcomes but which is not apparent without additional provocation.

Early fine motor impairment and behavioral dysfunction in (Thy-1)-h[A30P] alpha-synuclein mice.

Introduction: Intraneuronal inclusions of alpha-synuclein are commonly found in the brain of patients with Parkinson's disease and other α-synucleinopathies. The correlation between alpha-synuclein pathology and symptoms has been studied in various animal models. In (Thy-1)-h[A30P] alpha-synuclein transgenic mice, behavioral and motor abnormalities were reported from 12 and 15 months, respectively. The aim of this study was to investigate whether these mice also display symptoms at earlier time points. Methods: We analyzed gait deficits, locomotion, and behavioral profiles in (Thy-1)-h[A30P] alpha-synuclein and control mice at 2, 8, and 11 months of age. In addition, inflammatory markers, levels of alpha-synuclein oligomers, and tyrosine hydroxylase reactivity were studied. Results: Already at 2 months of age, transgenic mice displayed fine motor impairments in the challenging beam test that progressively increased up to 11 months of age. At 8 months, transgenic mice showed a decreased general activity with increased risk-taking behavior in the multivariate concentric square field test. Neuropathological analyses of 8- and 11-month-old mice revealed accumulation of oligomeric alpha-synuclein in neuronal cell bodies. In addition, a decreased presence of tyrosine hydroxylase suggests a dysregulation of the dopaminergic system in the transgenic mice, which in turn may explain some of the motor impairments observed in this mouse model. Conclusions: Taken together, our results show that the (Thy-1)-h[A30P] alpha-synuclein transgenic mouse model displays early Parkinson's disease-related symptoms with a concomitant downregulation of the dopaminergic system. Thus, this should be an appropriate model to study early phenotypes of alpha-synucleinopathies.

Dose-dependent effects of alcohol administration on behavioral profiles in the MCSF test.

The acute effects of alcohol administration are age-, dose-, time- and task-dependent. Although generally considered to be a sedative drug, alcohol has both stimulatory and depressant effects on behavior, depending on dose and time. Alcohol-induced motor activating effects are consistently shown in mice but rarely demonstrated in adult, outbred rats using conventional behavioral tests. The aim of the present experiment was to study acute alcohol-induced effects on behavioral profiles in a more complex environment using the novel multivariate concentric square field™ (MCSF) test, designed for assessing different behaviors in the same trial including locomotor activity. Adult male Wistar rats (Sca:WI) were administered one intraperitoneal (i.p.) injection of alcohol (0.0 g/kg, 0.5 g/kg, 1.0 g/kg, or 1.5 g/kg) 5 min prior to the 30-min MCSF test. The two highest doses induced marked motor-suppressing effects. A significant interaction between group and time was found in general activity when comparing rats exposed to alcohol at 0.0 g/kg and 0.5 g/kg. In contrast to the 0.0 g/kg dose that increased the activity over time, animals administered the low dose (0.5 g/kg) demonstrated an initial high activity followed by a decline over time. No indications for acute alcohol-induced anxiolytic-like effects were found. The multivariate setting in the MCSF test appears to be sensitive for detecting motor-activating effects of low doses of alcohol as well as reduced locomotion at doses lower than in other behavioral tasks. The detection of subtle changes in behavior across time and dose is important for understanding alcohol-induced effects. This approach may be useful in evaluating alcohol doses that correspond to different degrees of intoxication in humans.

Altered explorative strategies and reactive coping style in the FSL rat model of depression.

Modeling depression in animals is based on the observation of behaviors interpreted as analog to human symptoms. Typical tests used in experimental depression research are designed to evoke an either-or outcome. It is known that explorative and coping strategies are relevant for depression, however these aspects are generally not considered in animal behavioral testing. Here we investigate the Flinders Sensitive Line (FSL), a rat model of depression, compared to the Sprague-Dawley (SD) rat in three independent tests where the animals are allowed to express a more extensive behavioral repertoire. The multivariate concentric square field™ (MCSF) and the novel cage tests evoke exploratory behaviors in a novel environment and the home cage change test evokes social behaviors in the re-establishment of a social hierarchy. In the MCSF test, FSL rats exhibited less exploratory drive and more risk-assessment behavior compared to SD rats. When re-exposed to the arena, FSL, but not SD rats, increased their exploratory behavior compared to the first trial and displayed risk-assessment behavior to the same extent as SD rats. Thus, the behavior of FSL rats was more similar to that of SDs when the rats were familiar with the arena. In the novel cage test FSL rats exhibited a reactive coping style, consistent with the reduced exploration observed in the MCSF. Reactive coping is associated with less aggressive behavior. Accordingly, FSL rats displayed less aggressive behavior in the home cage change test. Taken together, our data show that FSL rats express altered exploratory behavior and reactive coping style. Reduced interest is a core symptom of depression, and individuals with a reactive coping style are more vulnerable to the disease. Our results support the use of FSL rats as an animal model of depression and increase our understanding of the FSL rat beyond the behavioral dimensions targeted by the traditional depression-related tests.

Subgroup-dependent effects of voluntary alcohol intake on behavioral profiles in outbred Wistar rats.

Experimental animal models are critical for understanding the genetic, environmental and neurobiological underpinnings of alcohol use disorders. Limited studies investigate alcohol-induced effects on behavior using free-choice paradigms. The aims of the present experiment were to study voluntary alcohol intake using a modified intermittent access paradigm, investigate the effects of voluntary alcohol intake on behavioral profiles in water- and alcohol-drinking rats, and select extreme low- and high-drinking animals for a more detailed behavioral characterization. Sixty outbred male Wistar rats were randomized into water and alcohol groups. Behavioral profiles in the multivariate concentric square field™ (MCSF) test were assessed prior to and after voluntary alcohol intake. The animals had intermittent access to 20% alcohol and water for three consecutive days per week for seven weeks. The results revealed increased alcohol intake over time. No major alcohol-induced differences on behavior profiles were found when comparing water- and alcohol-drinking animals. The high-drinking animals displayed an alcohol deprivation effect, which was not found in the low-drinking animals. High-drinking rats had lower risk-taking behavior prior to alcohol access and lower anxiety-like behavior after voluntary alcohol intake compared to low-drinking rats. In conclusion, the modified intermittent access paradigm may be useful for pharmacological manipulation of alcohol intake. With regard to behavior, the present findings highlights the importance of studying subgroup-dependent differences and add to the complexity of individual differences in behavioral traits of relevance to the vulnerability for excessive alcohol intake.

Risk-assessment and risk-taking behavior predict potassium- and amphetamine-induced dopamine response in the dorsal striatum of rats.

Certain personality types and behavioral traits display high correlations to drug use and an increased level of dopamine in the reward system is a common denominator of all drugs of abuse. Dopamine response to drugs has been suggested to correlate with some of these personality types and to be a key factor influencing the predisposition to addiction. This study investigated if behavioral traits can be related to potassium- and amphetamine-induced dopamine response in the dorsal striatum, an area hypothesized to be involved in the shift from drug use to addiction. The open field and multivariate concentric square field™ tests were used to assess individual behavior in male Wistar rats. Chronoamperometric recordings were then made to study the potassium- and amphetamine-induced dopamine response in vivo. A classification based on risk-taking behavior in the open field was used for further comparisons. Risk-taking behavior was correlated between the behavioral tests and high risk takers displayed a more pronounced response to the dopamine uptake blocking effects of amphetamine. Behavioral parameters from both tests could also predict potassium- and amphetamine-induced dopamine responses showing a correlation between neurochemistry and behavior in risk-assessment and risk-taking parameters. In conclusion, the high risk-taking rats showed a more pronounced reduction of dopamine uptake in the dorsal striatum after amphetamine indicating that this area may contribute to the sensitivity of these animals to psychostimulants and proneness to addiction. Further, inherent dopamine activity was related to risk-assessment behavior, which may be of importance for decision-making and inhibitory control, key components in addiction.

Postpartum Behavioral Profiles in Wistar Rats Following Maternal Separation - Altered Exploration and Risk-Assessment Behavior in MS15 Dams.

The rodent maternal separation (MS) model is frequently used to investigate the impact of early environmental factors on adult neurobiology and behavior. The majority of MS studies assess effects in the offspring and few address the consequences of repeated pup removal in the dam. Such studies are of interest since alterations detected in offspring subjected to MS may, at least in part, be mediated by variations in maternal behavior and the amount of maternal care provided by the dam. The aim of this study was to investigate how daily short (15 min; MS15) and prolonged (360 min; MS360) periods of MS affects the dam by examining postpartum behavioral profiles using the multivariate concentric square field (MCSF) test. The dams were tested on postpartum days 24-25, i.e., just after the end of the separation period and weaning. The results reveal a lower exploratory drive and lower risk-assessment behavior in MS15 dams relative to MS360 or animal facility reared dams. The present results contrast some of the previously reported findings and provide new information about early post-weaning behavioral characteristics in a multivariate setting. Plausible explanations for the results are provided including a discussion how the present results fit into the maternal mediation hypothesis.